sbc82xx: delete support for obsolete SBC8240/SBC8260

The EST SBC8260 is over 10 years old, and the SBC8240 older than
that.  With the tiny amount of RAM (by today's standards), there
really isn't anyone interested in running the latest U-boot on
these EOL products anymore.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
CC: jon.diekema@smiths-aerospace.com
16 files changed